Forth Inc[0] might qualify. The company was founded by Chuck Moore and Elizabeth Rather in 1971. Chuck invented Forth and Elizabeth was the second person to learn it.
If you leave out _new_, as the OP did, there's at least one example: Microsoft.
Re:An Early History of Pony
by digitalzombie on Sunday May 07, 2017 @12:06AM
(#14283790)
That's funny. Microsoft took the main guy from Pony.
They're really invested in languages like C# and F#.
I guess you gotta be a big established company to afford to maintain programming language. Google have Go. Ericsson got Erlang.
Any examples of successful startups based on a new programming language? Lightbend (previously Typesafe) worked on Scala, but the language existed before the company.